Conventional wisdom in the lead acid battery or storage battery art teaches that the negative electrode face of the separator should have either no ribs or ribs that extend in the longitudinal (i.e. vertical or machine) direction. See FIGS. 2 and 3 (discussed below). This understanding is based upon the generation of hydrogen gas at the negative electrode during overcharging. It was believed that if one were to place other than vertical or longitudinally extending ribs on the negative electrode face of the separator, then the hydrogen gas would be trapped under those ribs, and that this entrapped hydrogen gas would lead to an undesired reduction of efficiency of the battery. It was believed that an efficiency reduction would result from the hydrogen gas preventing the electrolyte from contacting a portion of the negative electrode surface. Thus, the effective surface area of the negative electrode would be reduced.
Referring to FIG. 2, a prior art separator 30 is illustrated. Separator 30 has a negative electrode side 32 and a positive electrode side 34 (the part folded over). The positive electrode side 34 includes a plurality of longitudinally extending major ribs 36. The negative electrode side 32 includes a plurality of longitudinally extending minor ribs 38. One difference between major ribs 36 and minor ribs 38 is their height, major ribs 36 being greater in height than minor ribs 38. Another difference is the spacing between the ribs, major ribs 36 being more spaced apart than minor ribs 38. Such a separator is commercially available from Daramic, LLC of Charlotte, N.C. under the trade name of DARANIC® in various versions.
Referring to FIG. 3, a prior art separator 40 is illustrated. Separator 40 has a positive electrode side 42 and a negative electrode side 44. The positive electrode side 42 includes a plurality of longitudinally extending ribs 46. The negative electrode side 44 (the part folded over) has no ribs. Such a separator is commercially available from Daramic, LLC of Charlotte, N.C. under the trade name of DARAMIC® in various versions.
U.S. Pat. No. 5,776,630 discloses a separator for use in accumulators having both longitudinal and traverse ribs located on the positive electrode face of the separator.
There is a need for improved or specialized separators for at least particular separator applications, methods of separator manufacture, methods of battery manufacture, methods of separator use, improved separator envelopes, improved batteries, and/or the like.